What is a wicking bed?

Wicking beds are basically large containers that store water at the bottom in reservoirs, working in the same way that self-watering pots do, but on a much larger scale.

Moisture is drawn up through the soil via the process called capillary action or wicking. This process ensures that the water is distributed evenly throughout the soil and all plants always have equal access to moisture.

How do you make one 101

The Container: You first need to acquire the container – wooden vegetable crates, Plastic IBC pod (cleaned and non-chemical) are common choices.

Liner: If using wooden crates, you will need to line them with a waterproof builders plastic, clamp this in place. And then add a layer of old carpet to line the bottom.

The Reservoir: a layer of gravel needs to be placed in the bottom on top of the carpet. 
Then a coil of ag pipe held in place with something weighted. Place around 10cm of gravel on top of the pipe. The ag pipe should be placed up against the side of the container attached to the PVC pipe that runs up the side to the top.
To separate the soil from this reservoir you can use shade cloth or geotextile fabric.

Overflow: Drill a hole in the side of the container where the gravel meets the soil, this will allow excess water to drain out and make sure the soil doesn’t become sodden. 

Position: Place wicking beds in a full sun flat position and fill with the best quality garden soil compost mix, then mulch on top. The soil depth needs to be a minimum of 30cm. 

Wicking will start to function properly after a week or so. Whilst this is taking time to settle in and function it is advisable to water the plants from the top for this first week.